Simultaneous wireless information and power transfer (SWIPT) is a promising solution to increase the lifetime of wireless nodes and hence alleviate the energy bottleneck of energy constrained wireless networks. As an alternative to conventional energy harvesting techniques, SWIPT relies on the use of radio frequency signals, and is expected to bring some fundamental changes to the design of wireless communication networks. This article focuses on the application of advanced smart antenna technologies to SWIPT, including multiple-input multiple-output and relaying techniques. These smart antenna technologies have the potential to significantly improve the energy efficiency and also the spectral efficiency of SWIPT. Different network topologies with single and multiple users are investigated, along with some promising solutions to achieve a favorable trade-off between system performance and complexity. A detailed discussion of future research challenges for the design of SWIPT systems is also provided.

/pdf/application-of-smart-antenna-technologies-in-simultaneous-1a2grunpar.pdf

Application of smart antenna technologies in simultaneous wireless information and power transfer

Mobile ad-hoc networking involves peer-to-peer communication in a network with a dynamically changing topology. Achieving energy efficient communication in such a network is more challenging than in cellular networks since there is no centralized arbiter such as a base station that can administer power management. We propose and evaluate a power control loop, similar to those commonly found in cellular CDMA networks, for ad-hoc wireless networks. We use a comprehensive simulation infrastructure consisting of group mobility, group communication and terrain blockage models. A major focus of research in ad-hoc wireless networking is to reduce energy consumption because the wireless devices are envisioned to have small batteries and be incapable of energy scavenging. We show that this power control loop reduces energy consumption per transmitted byte by 10-20%. Furthermore, we show that it increases overall throughput by 15%.

/pdf/distributed-power-control-in-ad-hoc-wireless-networks-9t9xhoxhsg.pdf

Distributed power control in ad-hoc wireless networks

Providing connectivity to around half of the world population living in rural or underprivileged areas is a tremendous challenge, but, at the same time, a unique opportunity. Access to the Internet would provide the population living in these areas a possibility to progress on the educational, health, environment, and business levels. In this article, a survey of technologies for providing connectivity to rural areas, which can help address this challenge, is provided. Although access/fronthaul and backhaul techniques are discussed in this article, it is noted that the major limitation for providing connectivity to rural and underprivileged areas is the cost of backhaul deployment. In addition, energy requirements and cost-efficiency of the studied technologies are analyzed. In fact, the challenges faced for deploying an electricity network, as a prerequisite for deploying communication networks, are huge in these areas, and they are granted an important share of the discussions in this article. Furthermore, typical application scenarios in rural areas are discussed, and several country-specific use cases are surveyed. The main initiatives by key international players aiming to provide rural connectivity are also described. Moreover, directions for the future evolution of rural connectivity are outlined in this article. Although there is no single solution that can solve all rural connectivity problems, building gradually on the current achievements in order to reach ubiquitous connectivity, while taking into account the particularities of each region and tailoring the solution accordingly, seems to be the most suitable path to follow.

/pdf/a-key-6g-challenge-and-opportunity-connecting-the-base-of-385d3hceqi.pdf

A Key 6G Challenge and Opportunity—Connecting the Base of the Pyramid: A Survey on Rural Connectivity

Transmission patterns for pilot symbols transmitted from a mobile station or base station are provided. The pattern allows for improved receipt of the pilot symbols transmitted. In addition, schemes for improving the ability to multiplex pilot symbols without interference and/ or biasing from different mobile stations over the same frequencies and in the same time slots.

Pilot signal transmission for an orthogonal frequency division wireless communication system

Apparatuses and methodologies are described that enhance performance in a wireless communication system using beamforming transmissions. According to one aspect, the channel quality is monitored. Channel quality indicators can be used to select a scheduling technique, such as space division multiplexing (SDM), multiple-input multiple output (MIMO) transmission and opportunistic beamforming for one or more user devices. In addition, the CQI can be used to determine the appropriate beam assignment or to update the beam pattern.

Channel quality reporting for adaptive sectorization

For mobile ad hoc networks used in network-centric operations, there is a growing need for a systematic methodology for analyzing/predicting the performance of the network over the mission duration. With the advance in cognitive networking as a possible means of exploiting unused spectrum, there is now a growing need to study how to design a cognitive network using an automated methodology. In this article we study the concepts and challenges for automatic design/ reconfiguration of cognitive MANETs. We describe the design objectives, imposed constraints, and involved parameters in MANETs. We describe how cognitive techniques can be employed to exploit the unused spectrum in military architectures. We then discuss the challenges facing the design/reconfiguration of a cognitive network and their implications at different network layers. We also describe possible implementation options for designing MANETs that employ cognitive features at all layers.

http://inforfang.persiangig.com/Journals/Cognitive%20MANET%20Design%20for%20Mission-Critical%20Networks.pdf

Cognitive MANET design for mission-critical networks

We consider the problem of MIMO channel estimation subject to a given error and delay constraints. Our objective is to minimize the energy spent during the channel estimation phase, which includes transmission of training symbols, storage of those symbols at the receiver, and also channel estimation at the receiver. We develop a model that is independent of the hardware or software used for channel estimation, and use a divide and conquer strategy to minimize the overall energy consumption.

Energy efficient channel estimation in MIMO systems

Mobile ad hoc networks have become the basis of the military's network-centric warfare (NCW) approach. However, for NCW to be successful, it is imperative that the networks be designed in a robust manner with the capability to produce consistent predictable results despite the uncertainties of the underlying environment. This underscores the need for formal systematic methodologies to design and predict performance of such networks. The challenges of mobile ad hoc networking combined with those associated with the stringent requirements posed by NCW systems, however, are daunting, and thus no systematic design techniques for NCW system design exist. To address this problem, a joint project was initiated between CERDEC and Telcordia Technologies to develop the Network Engineering Design Analytic Toolset (NEDAT) - a toolset that applies network-science-based approaches to design MANETs for use in NCW. Rooted in formal/analytic techniques, NEDAT can be used to design MANETs for use in NCW given information about available resources and performance objectives, analyze performance of a given NCW network, and understand design trades.

Network science based approaches to design and analyze MANETs for military applications

The emergence of MIMO communications systems as practical high-data-rate wireless communications systems has created several technical challenges to be met. On the one hand, there is potential for enhancing system performance in terms of capacity and diversity. On the other hand, the presence of multiple transceivers at both ends has created additional cost in terms of hardware and energy consumption. For coherent detection as well as to do optimization such as water filling and beamforming, it is essential that the MIMO channel is known. However, due to the presence of multiple transceivers at both the transmitter and receiver, the channel estimation problem is more complicated and costly compared to a SISO system. Several solutions have been proposed to minimize the computational cost, and hence the energy spent in channel estimation of MIMO systems. We present a novel method of minimizing the overall energy consumption. Unlike existing methods, we consider the energy spent during the channel estimation phase which includes transmission of training symbols, storage of those symbols at the receiver, and also channel estimation at the receiver. We develop a model that is independent of the hardware or software used for channel estimation, and use a divide-and-conquer strategy to minimize the overall energy consumption.

/pdf/energy-efficient-channel-estimation-in-mimo-systems-29zr0hwx0z.pdf

Energy-efficient channel estimation in MIMO systems

In this paper, we address the problem of establishing full connectivity and satisfying required traffic capacity between disconnected clusters in large wireless ad-hoc ground networks by placing a minimum number of advantaged high flying Aerial Platforms (APs) as relay nodes at appropriate places. We also extend the connectivity solution in order to make the network survivable to a single AP failure. The problem of providing both connectivity and required capacity between disconnected ground clusters is formulated as a summation-form clustering problem with inter-AP distance constraints that make the AP network fully connected and with complexity costs that take care of cluster to AP capacity constraints. The resultant clustering problem is solved using deterministic annealing to find (near) globally optimal solutions for the minimum number and locations of the APs to establish full connectivity and provide required traffic capacity between disconnected clusters. In order to make the network single AP survivable, the connectivity solution is extended so that each AP connects to at least two neighboring APs and each ground cluster connects to at least two APs. We establish the validity of our algorithms by comparing it with optimal exhaustive search algorithms and show that our algorithms are near-optimal for the problem of establishing connectivity between disconnected clusters.

C. Graff

Papers

Cognitive MANET design for mission-critical networks

Energy efficient channel estimation in MIMO systems

Network science based approaches to design and analyze MANETs for military applications

Energy-efficient channel estimation in MIMO systems

Aerial Platform placement algorithms to satisfy connectivity, capacity and survivability constraints in wireless ad-hoc networks